Metal-free lubricant additives and method for preparation thereof



Unite METAL-FREE LUBRECANT ADDITIVES AND NETHOD EUR PREPARATIUN THEREOF No Drawing. Application November 8, 1954- Serlal No. 467,661

7 Claims. (Cl. 252-4.4)

This invention relates to new compositions of matter which have particular utility as additives for use in lubricents. in a more particular sense it relates to certain sulfur-bearing, metal-free compositions which have dispersant qualitites when used in relatively small proportions in a motor oil.

In many internal combustion engines, especially diesel engines, where severe service conditions are encountered, there is a strong tendency for an objectionable amount or" resinous and varnish-like materials to become deposited upon the piston skirts and the piston rings, and in the ring grooves. The deposition of these materials may be controlled and largely prevented, and to some extent'may be removed after formation, by the use of certain types of additives in the lubricating oil.

Those additives which are presently used for this purpose include principally the metal salts of organic acids, especially he metal sulfonates. In some cases the normal sultonates are used but for most instances the basic or high metal-containing sulfonate compositions are employed. These latter compositions are particularly effective as dispersing agents for use in such severe lubricant applications, and their eliectiveness appears to be at least proportionate to their respective metal content. That is, the more metal contained in such a dispersant additive the greater is its efiectiveness in preventing the deposition of resinous and varnish-like materials upon the piston skirts and the piston rings and in the ring grooves.

The very presence of such large percentages of metal, even in apparently oil-soluble form, however, is a source of some concern. The metal complex, however oil-soluble, is nevertheless a potential source of harmful metallic ash deposit which may collect on one or more of the parts of an engine. The more metal there is present the greater is the possibility of such deposit collecting. For this reason some investigators have accepted with reservation the advent of high metal-bearing compositions as lubricant additives. These investigators have in fact directed their ellorts toward a search for a motor oil dispersant which contains no metal at all, a so-called ashless detergent.

it is accordingly a principal object of the present invention to provide a novel, oil-soluble composition of matter.

Another object is the provision of an ashless detergent.

Other objects will become apparent from the following description thereof.

To the accomplishment of the foregoing and related ends, said invention, then, comprises the features hereinafter fully described and particularly pointed out in the claims, the following description setting forth in detail cer ain illustrative embodiments of the invention, these eing indicative, however, of but a few of the various ways in which the principle of the invention may be employed.

The above and other objects are achieved by the invention described herein, whereby hitherto unknown compositions are made available. These compositions ice" rough they do not contain have dispersant qualities alt metal.

The novel composition of the present invention is prepared by the reaction of an olefinically unsaturated compound with thionyl chloride. The product of such a reaction is a metal-free sulfur-containing composition havparticularly desirable properties as a dispersing agent.

The olefinically unsaturated compound may be selected from a wide range of organic compounds including principally the olefins and olefinically unsaturated esters. Specific examples of such compounds include the followin amylene, isobutylene, diisobutylene, octene-l,. heptene, dodecene, unsaturated paraifin wax, dipentene, pinene, turpentine, ocimene, nonene, octadecene, polyisobutylene, polyamylene, polybutadiene, poly-nethyl methacrylate, polyethylene, polypropylene, diallzyl rnaleates fumarates, sperm oil, methyl oleate, glyceryl trilinoleate, methylcyclopentadiene, dicyclopentadiene, etc. Generally preferred are the olennic hydrocarbons having a molecular weight within the range of from about 159 to about 1500, with a special preference for polymers of ti e lower mono-olefins such as ethylene, propylene, butylene, amylene, hexylene, etc. coming within the above-stated molecular weight range.

The relative amounts of unsaturated compound and hionyl chloride which may be used in the process of this invention lie within the range of 0.2-5 .0 moles of thionyl chloride per mole of unsaturated compound. The mechanism of the reaction is not known nor is there a satisfactory understanding of the stoichiornetry involved.

The temperature of the reaction is preferably within the range of 50250 C. In most cases, the initial portion of the reaction is carried out at a relatively low temperature and then the reaction mixture is heated to a higher temperature to complete the reaction. A particularly suitable procedure as regards temperature is to heat the olefim'c compound at about 70-13 9" C. while adding the thionyl chloride portionwise; when all the thionyl chloride has been added the temperature of the resulting mixture then is raised to l8ll220 C. and held there at this level for an additional hour or so until the reaction is considered complete.

The product directly available from such a process is suitable for most purposes. If a particularly pure product is desired, the thus-obtained product may be washed with alkaline agents, etc. Generally, however, for use in most lubricants no purification of the product is required.

A particularly preferred process comprises heating the mixture of olefinically unsaturated compound and thionyl chloride in the presence of oxygen. Thus in such a process a stream of air may be bubbled through the hot olefinically unsaturated compound while simultaneously adding the thionyl chloride. The products available from this variant of the process are generally hghter in color and for this reason are somewhat more desirable.

As indicated earlier the product of the hereindescribed process is free of any metal. It does contain significant amounts of sulfur and in some cases appreciable amounts of chlorine, although the relative amounts of each differ from one product to another so that a precise estimation of the structure of these products is not possible.

Example 1 To 682 grams (2.0 moles) of di-(Z-cthylhexyl) maleate at 190 C., there was added dropwise over a two-hour period, 119 grams (1.0 mole) of thionyl chloride. The resulting mixture was heated for an additional two hours at 190200 C. and then concentrated by heating to a final temperature of C./ 16 mm. The clear, brown, oil-soluble liquid residue showed the following analyses:

Example 2 Nine hundred grams (2.1 moles) of sperm oil was' heated at l90200 C. while 251 grams (2.1 moles) ofthionyl chloride was added'dropwise thereto; When all the/thionyl chloride had been added, the mixture was heated at this same temperature for two hours and then filtered through'Hyfio. The filtrate. was a clear, oilsoluble' liquid having the following analyses:

Percent chlorine 0.3 Percent sulfur 3.4

Example 3 To 900 grams (3.0 moles) of methyl oleate at 190 C., there was added dropwise throughout a three-hour period, 361 grams (3.0 moles) of thionyl chloride. This temperature was maintained for an additional two hours and then filtered throug'h Hyflo. The clear, brown, oil-soluble filtrate showed the following analyses:

Percent chlorine 1.6

Percent sulfur Example 4 With nitrogen bubbling through 1000 grams (1.3 moles) of a polyisobutylene fraction having an average molecular weight of 750, there was added beneath the surface 159 grams (1.3 moles) of thionyl chloride. The temperature was maintained at 68-70 C. throughout the addition. This mixture then was heated gradually over a period of two and one quarter hours to 200 C. The brown, viscous, oil-soluble liquid showed the following analyses:

Percent chlorine 1.6 Percent sulfur 0.6

Example 5 Percent chlorine -i 0.83 Percent sulfur Example 6 To 500 grams (0.67. mole) of a polyisobutylene fraction having an average molecular weight of '750, there was added at l40180 C., 158 grams (1.3 moles) of thionyl chloride. The thionyl chloride was added heneath the surface of the polyisobutylene and the portionwise addition required thirty minutes. The resulting mixture was heated to 200 C. to yield a brown, viscous, oilsoluble liquid having the following analyses:

Percent chlorine Percent sulfur Example 7 To 375 grams (0.5 mole) of polyisobutylene (average molecular weight, 750) at 108-124? 0., there was added over a period of thirty minutes 119 grams (1.0 mole) of thionyl chloride. Then the mixture "was heated for an additional two and one half hours at this same temperature. This product was concentrated by'heating to' a:

final temperature of 125 C./30 mm. The residue was 4. a brown, viscous, oil-soluble liquid with the following analyses:

Percent chlorine -1. 2.5

Percent sulfur 3.0

Example 8 To 637 lbs. (.85 mole) of polyisobutylene (average molecular weight: 750) at 207214 C. there was'added portionwise over a period of 4.25 hours 303 lbs. (2.55 moles) of thionyl chloride. The thionyl chloride was added beneath the surface of the polyisobutylene. The resulting mixture was'heatedat2052l0 C. for an additional 30 minutes then filtered through a filter aid to yield a clear, liquid, oil-soluble product having the following analyses:

Percent chlorine Percent sulfur Example 9 To 938 grams (1.25 moles) of polyisobutylene (average molecular weight: 750) at 70 C. there was added portionwise over a period of 15 minutes 149 grams (1.25

moles) of thionyl chloride. The resulting mixture then was heated to 200 C. over a 4.0 hour period, and held at that temperature for an additional 30 minutes. The clear, oil-soluble residue showed the following analyses:

Percent chlorine Percent sulfur Example 10 To 3750 grams (5.0 moles) of polyisobutylene (average molecular weight: '750) at ZOO-220 C. there was added portionwise over a period of 3.7 hours 1783 grams (15 .0 moles) of thionyl chloride. The resulting mixture was stirred for an additional 30 minutes at 200 C./ 15 mm. to yield a clear, viscous, oil-soluble liquid having the following analyses:

Percent chlorine Trace Percent sulfur 4.64

Example 11 A sample of polyisobntylene (average molecular weight: 750) weighing 750 'grams (1.0 mole) was treated at 104 C. with 238 grams (2.0 moles) of thionyl chloride. The thionyl chloride was added portionwise over a period of 1.25 hours and air was bubbled through the mixturethroughout this period; The resulting mixture was then heated to 200 C. over a period of 1.5 hours and then allowed to cool. The resulting oil-soluble product showed the following analyses:

Percent chlorine Percent sulfur Example 12 Thionyl chloride (901 grams, 7.5 moles) was added portionwise over a period of 3.5 hours to 2500 grams (7.6 moles) of polyisobutylene (average molecular weight: 330). The reaction temperature was maintained at 70-80 C. throughout the addition and then was raised,

slowly to200 C. over'a 5-hour period and held at that point for an additional hour. The oil-soluble product showed the following analyses: 7

Percent chlorine 1.2 Percent sulfur Example 13 The procedure'of Example 12 was repeated 'using 833 grams (7.0 moles) of thionyl chloride and 1155 grams (3.5 moles) of polyisobutylene (molecular weight: 330) and adding the thionyl chloride at 40 C. The resulting oil-soluble product showed the following analyses:

The metal-free products which are available from the process of this invention are eminently useful as lubricant additives. They serve to alleviate a large proportion of the deleterious effects of a mineral oil lubricant, while at the same time of course, presenting no disadvantage as a source of metal-containing deposits. The efiectiveness of these metal-free additives is such that small amounts are satisfactory for some purposes. As little as 1 percent by weight has an appreciably beneficial effect, and larger amounts are proportionately more eflfective, as much as 12-15 percent by weight or more being desirable and yet sufficiently economical to find application as some lubricants.

The benefits imparted to a lubricant by the hereindescribed products are those which generally are attributed to a dispersant, viz. they tend to prevent the deposition of lacquer and varnish, etc. on the engine parts. Thus a lubricant containing a small amount of such product will in general prevent engine parts from becoming dirty. This feature is emphasized by results of a particular fullscale engine test in which a one-cylinder, 4-cycle diesel engine is operated under certain specified conditions for 120 hours. The test is an adaptation of the L-l Engine Test, CRC Designation L-l-545. In the official description of this test, there appears the following:

Scope (1) This procedure is intended for determining the effect of engine oils on ring-sticking, wear, and the accumulation of deposits under endurance conditions. While the test is carried out in a compression-ignition engine of the high-speed type, experience has shown that this procedure also correctly evaluates oils for use in heavy-duty spark-ignition automotive engines.

This procedure will evaluate the following qualities of engine oils under endurance test conditions:

.(a) The tendency of the engine oil to form materials in the ring grooves which bind the rings and prevent their free action, resulting in ring-sticking.

('b) The tendency of the engine oil to form excessive lacquer deposits on the piston resulting in improper heat transfer.

The tendency of the engine oil to form deposits at the top of the cylinder which cause piston crown scufling.

(d) The efficiency of the engine oil in reducing piston ring and cylinder wear.

The adaptation of the test conditions involve a reduction in time from 480 hours to units of 120 hours each and the use of fuel which contains 1 percent sulfur. This latter variation makes the procedure a considerably critical test as regards detergency since sulfur-containing fuels contribute seriously to the formation of lacquer and varnish deposits.

The results of such a test are determined by visual inspection of the piston, rings, etc. as follows:

(1) Percentage of the volume of the oil ring groove which is occupied by deposits.

(2) Overall cleanliness of the ring-belt area of the piston, i. e., the portion of the piston below the oil ring groove (100 meaning perfectly clean).

The following tabulation of results shows the utility of the products of the present invention, when used in a Mid- Continent SAE 30 oil which also contains 0.5 percent by weight of a zinc alkyl phosphorodithioate inhibitor.

Percent chlorine Percent sulfur The effectiveness of the above lubricants is apparent from the data shown. It will be noted that a negligible volume (1.0 percent) of deposits had collected in the oil ring groove even after 240 hours of operation in the case of lubricant A, and furthermore that the piston cleanliness ratings in all instances were very good.

A further test of detergency involves the performance of a lubricant in a single cylinder, liquid-cooled, Buda diesel engine.

The test conditions include hours of operation as follows:

Load, 5 brake horsepower Speed, 1800 R. P. M.

Fuel, diesel oil containing 1% of naturally-containing sulfur Fuel consumption, 3.05 lbs/hr.

Lubricant temperature, F.

Coolant temperature, 200 F.

At the conclusion of the 100 hours the engine is inspected particularly for overall piston cleanliness (perfectly clean=100), extent of deposits in the top ring groove (perfectly clean=l0).

The following test results were observed (percentages are by weight based on total lubricant):

Rating Lubricant Piston Top ring cleanligroove ness 0. Mid-Continent SAE 30 oil 45. 9 4. 6 D. 0+6 percent of the product of Example 8 62. 3 4. 5

E. 0+3 percent of the product of Example 8+0.5 1

percent of A 65. 6 5. 8

F. 0+6 percent of the product of Example 8+0.5

percent of A 63. 6 3.7

G. G+8A5 percent of the product 01 Example 10+0.5 percent of A 76.1 7. 4

H. O+8.75 percent of the product of Example 8+0.3 2 percent of B 65. 2 4. 3

1 A=a zinc alkyl phosphorodithioate inhibitor.

1 B =a Past-turpentine reaction product inhibitor.

The above ratings, it will be noted, point up the beneficial eflfect of the olefin-thionyl chloride reaction prodacts in that they enable a lubricant to maintain better overall piston cleanliness.

Other modes of applying the principle of the invention may be employed, change being made as regards the details described, provided the features stated in any of the following claims or the equivalent of such, be employed.

1 therefore particularly point out and distinctly claim I as my invention:

1. The process of preparing metal-free, sulfurand chlorine-containing materials which comprises heating at 50-250 C. for a period of time sufi'icient to insure completion of the subsequent reaction a mixture of an olefinically unsaturated aliphatic compound selected from the class consisting of polymers of ethylene, propylene, butylene, amylene and hexylene, and aliphatic carboxylic esters with thionyl chloride.

2. The process of claim 1 characterized further in that the process is carried out in two stages, the first 4. As a new composition of matter a product formed V by the .process of claim -1.

5. The process of claim l c haracteriged furthjer' in that} the olefinically unsaturated compound is polyisobutylene. v a

'6. The process of clain'r 1 characterized further in 10 that the olefinically unsaturated compound is sperm oil.

7. A lubricating campqsitiei1- containing v a major amount of a1 mineral oil and from .about' 1.0 116- about 12.0 percent rbyn weight of alp'roduct formed by {the process of claim V 7 References Cited in the file of this'pate' nt' V. '3 UNITED STATES PATENTS 2,264,319 Lincoln";..;.. Dec. 2,1941 2,313,611 Abrainowitz Mar. 9; 1943 2,549,425 Cashman Apr. 17,1951 

1. THE PROCESS OF PREPARING METAL-FREE, SULFUR- AND CHLORINE-CONTTAINING MATERIALS WHICH COMPRISES HEATING AT 50-250*C. FOR A PERIOD OF TIME SUFFICIENT TO INSURE COMPLETION OF THE SUBSEQUENT REACTION A MIXTURE OF AN OLEFINICALLY UNSATURATED ALIPHATIC COMPOUND SELECTED FROM THE CLASS CONSISTING OF POLYMERS OF ETHYLENE, PROPYLENE, BUTYLENE, AMYLENE AND HEXYLENE, AND ALIPHATIC CARBOXYLIC ESTERS WITH THIONYL CHLORIDE. 